#include <stdio.h>

void swap(int *p, int *q){
 int temp = *p;
 *p = *q;
 *q = temp;
}

int main(){
	int a = 1, b = 2;
	printf("a:%d, b:%d\n", a, b);
	swap(&a, &b);
	printf("after swap: a:%d, b:%d\n", a, b);
}
